If i buy a body control module for a 1999 grand am at pull a part, would i still have to get it reprogrammed?

The answer is - it depends.

Is the BCM out of the exact same year, and generally the same option package (SE, LE, SSE, etc) as your Grand Am (I am assuming this is to replace a BCM in your own '99 Grand Am)? Generally speaking I would say no it does not.

However here are some things to consider:

Note the condition of the car its coming out of (I am assuming for the moment that you pulled it out of the donor car yourself and it was not lying on the shelf at the wrecking yard already). Does it look like there was significant damage to the interior or wiring prior to you getting there - from either an extremely severe accident or possibly a fire? Has a lot of rain/moisture been allowed to get into the vehicle/BCM since getting to the wrecking yard (e.g. are the seats/carpet soaking wet due to busted windshields or missing doors?).

These would be signs that the BCM may need to be re-programmed or at least bench tested because of the what donor car has experienced either in an accident or since getting to the wrecking yard.

I found a way to program this bcm, but the air bag light still comes on, 2 modules later. Could it possibly need the bcm and the ecm both need to be flashed?